With the aid of microtomes, the histological samples taken from a patient are first embedded in paraffin and sectioned into thin sections, which are then applied onto specimen slides and, after treatment and coverslipping, delivered to a microscope for further investigation. Cryostat microtomes, which are used to section frozen samples that, for reasons of time, cannot go through the laborious preparation process for paraffin embedding. Depending on environmental conditions, however, it may also be necessary to cool the samples that are embedded in paraffin so as to prevent an unusable sectioning result due to soft paraffin.
Microtomes in which the sample holder on which the sample is mounted is arranged in a cooled chamber through which a cooled air flow is guided for cooling, are known. The cooling that occurs with these microtomes is only a relatively imprecise cooling that is often also not sufficient for sensitive samples. To avoid this, microtomes are also known in which a compression-type refrigerating machine (as known, for example, from commercially usual refrigerators) is provided, by which the sample holder is actively cooled. A microtome of this kind is known, for example, from the document WO 2004/029588 A1.
For sectioning of the sample, the sample holder is moved relative to the sectioning unit. In particular, the sample holder performs both a sectioning motion and a feed motion. As a result of the movement of the sample holder, the lines through which the refrigerant of the compression-type refrigerating machine is guided are under constant dynamic stress; especially in the case of the thin capillary tubes through which the refrigerant is delivered to the sample holder, this results in rapid material fatigue and thus in breakage of the capillary tube. The capillary tubes must therefore be replaced frequently, which is associated with corresponding labor and cost.
DE 94 21 559 U1 discloses a cryostat microtome in which the specimen holder is connected via capillary tubes to a refrigeration unit.
EP 1 811 280 A1 discloses a microtome in which the region in which the sample is microtomed is cooled.
U.S. Pat. No. 3,191,476 A discloses a microtome in which a gaseous temperature-control medium is delivered via a corrugated tube.
What is needed is an apparatus for sectioning histological samples with which the samples can be reliably cooled, and which has a long service life.